[TowerTalk] SPG & Service Entrance Grounds.

[Gary Schafer]

> -----Original Message-----
> From: towertalk-bounces at contesting.com [mailto:towertalk-
> bounces at contesting.com] On Behalf Of Phil Camera
> Sent: Wednesday, September 12, 2007 7:25 AM
> To: towertalk at contesting.com
> Subject: [TowerTalk] SPG & Service Entrance Grounds.
> 
> A couple of points to clarify from recent posts:
> 
> "Now I am confused Gary. I thought the tower ground was tied in with
> everything else. Unless, like a friend of mine who's tower is 300 ft from
> his house. If the tower is near the house,  I thought it was supposed to
> be
> tied into the SPG with everything else. Using more ground rods and cable
> spaced 16ft (or twice the length of the ground rod) apart."
> 
> 
> Mike you are correct.  If the tower is close enough, bond its grounding
> system to the SPG, if it's really far away, then leave them separate.
> 
> 
> "If the power and phone grounds are a long ways or on the other side of
> the
> > house, it is best to run a power feed over to your single point ground
> > panel
> > and place a suppressor on it at the panel rather than rely on a long
> bond
> > between the power panel and your single point ground panel."
> 
> This would be optimum but if you use large enough bonding wire or wide
> copper strap, you can achieve a low enough resistance/impedance bond
> between the two.  Personally I use #4 bare solid for my bonding wires.
> 
> Ideally, and what most commercial stations do, is install a perimeter
> grounding system around the entire structure and then you can just tap
> onto that and you're good to go regardless of entrance location of the
> service, phone, or coaxes.

> > 
> --
> Phil - KB9CRY
> Lockport, IL

Hi Phil,

When you run any length of ground conductor over to your power entrance and
you don't have your power run thru your single point ground panel, you
technically don't have a single point ground system. You may have everything
bonded to one place but there is still a possibility for voltage differences
between those points. 

Neither is a system with a perimeter ground grounding system with equipment
"taped" into the ground ring a true single point ground system.

Some companies used to run a ground ring around the inside of buildings and
tap into that ring with each piece of equipment. Most have gotten away from
that sort of grounding idea as it left pieces of equipment in series with
each other on the ground ring. In other words one piece of equipment was
closer to the earth connection than the next.

Sometimes these alternatives are all that can be done at a particular site
but they are not "single point ground systems" and should not be called
such.

The best way is to have your coax entrance panel right at the power entrance
point and also the phone line entrance point there too, and any other cables
that connect to equipment that come in. All connected to the same panel
before going to your equipment.

If you can't do that then the next best thing to do is to run a power line
over to your coax panel, put power line suppressors on the panel and feed
your equipment from there. Same with phone lines and any other cables.

If it is a very short run over to the power entrance panel from the coax
entrance panel you can get by with heavy strap between panels.

The whole idea of a single point ground panel is to have near zero impedance
between any lines feeding equipment.

The purpose of a perimeter ground around a building should be to help
equalize voltages in the ground around the building to equalize ground
conducted currents from lightning. It should not be there as a convenient
tie point for equipment unless there is no other way to bond everything
together.

73
Gary  K4FMX